1. Field of the Invention
Aspects of the present invention relate to an image forming apparatus and a speed control method thereof.
2. Description of the Related Art
Peripheral devices, such as printers, scanners, and multifunction devices, are currently being actively developed. In particular, manufactures have developed laser printers having enhanced printing quality, higher printing speeds, and less operating noise, as compared to conventional dot matrix and inkjet printers.
A laser printer performs printing operations, such as charging, writing, developing, transferring, and fusing, to print images. Charging refers to applying a high voltage (approximately 7000V) to a charging unit and forming a negative electric charge on the surface of a drum, using a coronal discharge. Writing refers to scanning a laser beam onto the surface of the charged drum, to form a latent image thereon. Developing refers to applying negatively charged toner particles to the latent image, using a developing roller that rotates in close proximity to the drum. Transferring refers to using a transfer unit to apply a positive transfer voltage to paper passing between the drum and the transfer unit, so that the toner particles on the surface of the drum are transferred to the paper. Fusing indicates fusing the toner to the paper, using heat and pressure.
A color printer forms color images using four different toners, such as cyan, magenta, yellow, and black toners. In order to more clearly print images, different organic photo conductors (OPC) are used for each of the four toners. In this case, in order to precisely transfer each toner to paper, the location of a groove on the intermediate transfer belt (ITB) is determined, so that drums of the OPCs can be synchronized with a transfer roller.
In general, if an image forming apparatus completes printing, the image forming apparatus enters a standby period, to receive any subsequent printing command, before starting a post-printing process. This is because a user may input printing commands individually, rather than inputting printing commands simultaneously, or because a plurality of documents may be commonly printed, once printing is started.
If a post-printing process is performed promptly after completing printing, and a subsequent printing command is input during the post-printing process, a pre-printing process is be performed after the post-printing process is completed, thereby causing inconvenience. Therefore, an image forming apparatus generally enters a standby mode after completing printing, to wait for a subsequent printing command.
However, when printing is performed using the above-described ITB, if a printing command is received during a standby period, the image forming apparatus generally waits until an ITB signal is received, before resuming printing, which delays the printing. Therefore, there is a need for methods of reducing a printing time.